Disclosed herein are a method and apparatus for generating a spread spectrum signal in a printer power supply unit, as well as corresponding apparatus and computer-readable medium.
In many print engines, alternating current (AC) driven corona devices are employed because they provide very good charge uniformity. They have historically been driven with a 4 KHz high voltage AC source, which was chosen as a good compromise between the potential for creating image quality problems at low frequencies and increasing reactive power demands at higher frequencies.
One problem with the use of these devices has been the audible noise they generate. The 4 KHz signal falls well within the frequency range of the hearing of most people, and the more devices that are employed, the more annoying the audible noise can be to others. In addition, two other potential problems that can be associated with these devices are the possibility of producing image quality artifacts, even at 4 KHz, and the ubiquitous presence of electromagnetic (E/M) emissions which are concentrated at high harmonics of the fundamental frequency.